1. Field of the Invention
The present invention relates to a power source circuit having a charge function applicable to an equipment with a chargeable driving mechanism, and a printer having a charge function applicable thereto and connected to or contained within an image forming apparatus such as a copying machine, a personal computer, or a word processor. Particularly, the present invention is more effective for use with an ink jet recording apparatus which records by discharging the recording liquid onto a recording medium such as a paper or film.
2. Related Background Art
Conventionally known charging methods can be largely classified into the constant current method such as standard charge (non-control), short time charge (non-control, timer control method), and quick charge (voltage control method, V taper control method), and the constant voltage method. As the former, typical of a chargeable secondary cell (battery) is a NiCd secondary cell, and as the latter, a carbon lithium or vanadium lithium secondary cell are known.
On the other hand, the copying machine or ink jet printer having the secondary cell has been put to practical use, in which the charging method is often separately provided, and expensive. This fact opposes to a requirement for the printer that the apparatus should be smaller, lighter and in lower cost.
The present invention was achieved from the point of the charging method in view of the above state of the art, because it is incorrect to utilize a battery which may not effect a sufficient accumulation of electricity by charging, so that the charge is attempted many times wastefully, or in the extreme case, a problem is caused that a charge circuit may be destroyed.
However, even if the inexpensive constitution of judging the battery life might be created, there was a tendency of increasing the judging time.
It is a main object of the present invention to provide a power source circuit having a reliable and inexpensive charge function which allows the judgment in a relatively short time, without damaging the charge function, and it is a further object to provide a suitable charge function for the cheap, small printer.
Typical of the present invention is a power source circuit as a first embodiment comprising a charge circuit for charging a chargeable battery, and having a charge function characterized by including a circuit for detecting a battery voltage of the battery after the passage of a predetermined period at a charge voltage rising stage since the start of charging, means for judging the life of the battery by comparing a detected result of the detecting circuit with a reference value, and means for stopping the charge of the battery in accordance with the judgment of a battery failure by the judging means, and a printer as a second embodiment comprising a power source circuit including a charge circuit for charging a chargeable battery for use in recording with recording means, characterized in that the printer comprises means for detecting a battery voltage of the battery after the passage of a predetermined period at a charge voltage rising stage since the start of charging, means for judging the life of the battery by comparing a detected result of the detecting circuit with a reference value, and means for stopping the charge of the battery in accordance with the judgment of a battery failure by the judging means.
These present embodiments were achieved by noticing that the variation in the charging state for an abnormal battery with its span of life exhausted was different from that for a normal battery, as a result of examining the rising state of the battery voltage at the charging stage, and concluding that the judgment could be performed even at the early stage from the start of charging.
According to the present invention, a cheap, quick and reliable judgment can be accomplished, so that it is possible to provide a power source circuit with an improved reliability of the charge function and without wasted operation time, and particularly, a printer with the recording unusable time largely reduced.
Next, the characteristics of a further preferred embodiment will be described in the following.
The judgment criterion of the present invention is such that the difference between the curves 1 and 2 of FIG. 10 as will be described later is judged, but to accomplish a further longer life of the charge function, the reference value as above mentioned is set to be the same value as a rating of the battery (including a rating of about -0.5V in a substantially equivalent sense), and the predetermined period as above mentioned is preferably within several minutes after starting of the charge during which the normal battery can exceed the reference value. This is because the charge function itself is set to allow a stable charge for the rating of the battery.
Next, to realize a lower price of the whole apparatus, the charge circuit is composed of transistors, current control resistors and a temperature fuse arranged in parallel with the resistors, and the charge stopping means has preferably a function of indicating battery trouble.
Since the battery voltage may be changed in a range from about 2V to 5V due to the environmental temperature, it is further preferable to correct for this variation so that there is no influence with the variation. Specifically, considering the temperature elevation in the service condition, it is preferable that the detecting circuit or the judging means has means for correcting for the detected result or the reference value in accordance with the environmental condition. This correction can be made by increasing the detected voltage with the elevation of temperature, or decreasing the reference value. As another method, it is also preferable to control the charge to be stopped after performing plural times of the judgment, thereby making the final judgment after stabilizing the measurement state against the temperature elevation. Herein, it is also included that the failure is once judged for the apparatus, and then the final judgment is made by making the above judgment to obtain a reconfirmation of changing the battery.
As for the printer, it is also preferable in practical use that the above reference value is made a voltage at which the recording can be accomplished with the recording means or a voltage at which means for maintenance of the recording head can be activated. This maintenance means includes a cap or cleaning means as will be described later, for example, but is not limited to them.
The present invention is suitable particularly to the printer comprising a thermal recording head for recording by the use of thermal energy as the recording means and a recording medium to be recorded so that they are movable relative to each other, and further to an ink jet recording apparatus in which the ink is discharged by the use of the film boiling of ink which is caused by thermal energy.
Moreover, another representive aspect of the present invention is a recording apparatus as a third embodiment comprising a power supply circuit having a charge circuit for charging a chargeable battery, wherein the recording apparatus has a charge function characterized by comprising a circuit for detecting a power supply voltage before starting of the charge or during the charge, means for judging whether or not the charging power is supplied by comparing a detected result of the detecting circuit with a reference value, and means for stopping the charge of the battery in accordance with the judgment of a failure by the judging means, and as a fourth embodiment, a recording apparatus having a power source circuit including a charge circuit for charging a chargeable battery for use in recording with recording means, characterized by comprising means for detecting the battery voltage of the battery before charging in a charge mode, means for judging the mounting state of the battery by comparing a detected result of the detecting circuit with a reference value, and means for indicating the absence of a battery in accordance with the judgment of a battery failure by the judgment means.
According to the third embodiment of the present invention, it is possible to sufficiently cope with the change of the charge state which is typical of an absence of an adaptor during the charge process, thereby resolving a charge failure or a disadvantage of consuming wastefully the previously charged power. Particularly, a cheap, quick and reliable judgment can be accomplished, providing a recording apparatus with an improved reliability of the charge function and without a wasteful operation time.
According to the fourth embodiment of the present invention, the charge function can be accommodated without any mechanical judgment, and as a whole, a cheap, quick and reliable judgment can be accomplished, providing a recording apparatus with an improved reliability of the charge function and without a wasteful operation time.
To realize a lower price of the whole apparatus, the charge circuit is composed of transistors, current control resistors and a temperature fuse arranged in parallel with the resistors, and the charge stopping means has preferably a function of indicating battery trouble.
Since the battery voltage may change in a range from about 2V to 5V due to the environmental temperature, it is further preferable to correct for this variation so that there is no influence with the variation. Specifically, considering the temperature elevation with the service condition, it is preferable that the detecting circuit or the judging means has means for correcting for the detected result or the reference value in accordance with the environmental condition. This correction can be made by increasing the detected voltage with the elevation of temperature, or decreasing the reference value. As another method, it is also preferable to control the charge to be stopped after performing plural times of the judgment, thereby making the final judgment after stabilizing the measurement state against the temperature elevation. Herein, it is also included that the failure is once judged for the apparatus, and then the final judgment is performed by making the above judgment to obtain a reconfirmation of changing the battery.
As a maintenance means, a cap or cleaning as will be described later is included, for example.
Also, addition of a restoration means for the recording head, a preliminary auxiliary means, etc. provided as the constitution of the recording device of the present invention is preferable, because the effect of the present invention can be further stabilized. Specific examples of these may include, for the recording head, capping means, cleaning means, pressurization or suction means, electricity-heat converters or other type of heating elements, or preliminary heating means according to a combination of these, and it is also effective for performing stable recording to perform a preliminary mode which performs discharging separate from recording.
Further, as the recording mode of the recording device, the present invention is extremely effective for not only the recording mode only of a primary color such as black, for example, but also a device equipped with at least one of plural different colors or full color by color mixing, whether the recording head may be either integrally constituted or combined in plural number.
Another embodiment as will be described in the example of the present invention is significant in the art and preferable for the present invention. The present invention will be more clearly understood from the following description.